The damaging action of the ultraviolet part of solar radiation on the skin is generally known to those skilled in the art. Depending on its particular wavelength, the rays have various actions on the organ skin. The “UV-C radiation” having a wavelength which is smaller than 290 nm, is absorbed by the ozone layer in the earth's atmosphere and therefore has no physiological importance. However, rays in the range between 290 nm and 320 nm, i.e., the “UV-B range”, cause erythema, simple sunburn or even more or less severe burns. The narrower range around 308 nm is indicated as a maximum of the erythema activity of sunlight.
Approximately 90% of the ultraviolet radiation reaching the earth consists of UV-A rays. While the UV-B radiation varies greatly, depending on numerous factors, such as the time of year and day or latitude, the UV-A radiation, independently of time of year and day or geographical factors, remains relatively constant day by day. At the same time, the major part of the UV-A radiation penetrates into the living epidermis, while approximately 70% of the UV-B rays are stopped by the horny layer.
It is therefore of fundamental importance that cosmetic sunscreen preparations offer adequate protection both against UV-B radiation and against UV-A radiation.
The prior art is also familiar with products for the care of the skin, which are used after sunbathing and customarily contain special active ingredients, such as, for example, refatting agents and moisturizers, inflammation-relieving and cooling substances, locally anesthetizing substances and/or disinfecting substances, in order, for example, to prevent possible skin infections. These “aftersun” or “après-soleil” preparations are intended to cool the skin after sunbathing and to improve its moisturizing power, the mediation of the cooling effect playing a central role. However, the prior art lacks products which protect the skin from drying out and adequately care for it even during UV irradiation.
One disadvantage of the prior art is that customary sunscreen formulations and products for the care of the skin leave behind a film, which is usually tacky, on the skin. When using such products on a sandy beach, this has the result that the sand remains stuck to the body, which is sensed as unpleasant by the user and can lead to the sunscreen formulations and products for the care of the skin being used too little or not at all. Since a wind of greater or lesser strength usually prevails on the beach, this disadvantage as a rule occurs even if the body does not come directly into contact with the sand at all, for example when sunbathing in a wicker beach chair or deckchair, since the sand dust spun round in the wind also remains stuck to the parts of the skin on which the prior art cream has been applied.